Vehicle washing services have been known for decades. Often such washing services utilize washing machines that are designed to wash particular portions of the vehicles. For example, one known type of washing machines has a relatively large and long brush rotating about a generally vertical axis that is used to wash vertical surfaces of the vehicle as the vehicle moves past the washing machine. The vehicle is either driven or conveyed past the washing machine. With some washing machines, one or more rotating vertical brushes are stationary and simply wash one or more side surfaces as the vehicle moves past the brushes. With other machines, a rotating brush is located at one side of the vehicle and is moved along a path parallel to the path of vehicle travel.
With still other machines, a brush is mounted at the distal end of a pivot arm having its proximal end pivotally connected to a frame above the vehicle, and the brush is used to wash one side and one or both ends of the vehicle. A critical design decision with such machines is the determination of where to mount the proximal end of the arm with respect to the centerline of the vehicle. In order to best wash the front end of a vehicle, the proximal end of the pivot arm should be mounted in an outside position close to the side being washed. Thus, in washing the front of the vehicle starting at the center, as the vehicle moves forward, the pivot arm extends outward, thereby allowing the brush to move forward as it moves across the front of the vehicle. However, after the brush has washed the side of the vehicle, as the brush moves around the rear of the vehicle, the outside location of the pivot point results in the pivot arm moving the brush away from the vehicle simultaneously with the vehicle moving away from the brush. The net result is that as the brush moves across the rear of the vehicle, the force of its contact with the vehicle is constantly diminishing, thereby producing an equally diminishing washing action and a poorer quality wash.
The ability of the brush to wash the rear side may be improved by moving the pivot point of the arm inward. Therefore, as the brush begins washing from one side of the rear, as the vehicle moves forward, the pivot arm rotates toward the vehicle, thereby maintaining the brush in contact with the rear of the vehicle. While the quality of the washing action on the rear end of the vehicle is improved with the more inward location of the pivot point, the quality of the washing action on the front end of the vehicle is reduced. When washing the front end of the vehicle, when pivot point of the arm is inward, as the pivot arm moves from the center of the front end toward one side, the vehicle is moving forward, but the arc of the pivot arm is moving the brush toward the vehicle. With the brush moving toward the vehicle, the forces between the brush and the front end of the vehicle build up very rapidly, thereby increasing the speed of the brush as it moves across the front end. The speed of the brush may be great enough that the brush loses contact with the vehicle as it moves around the front corner of the vehicle. In other situations, since the brush is rotating on a flexible spindle, the forces may be great enough to propel the rotating brush off of the front end and up over a portion of the hood of the vehicle.
Thus, the location of the pivot point of the arm with respect to the vehicle centerline results in a compromise with respect to the ability of the washing machine to wash either or both the front and rear ends of the vehicle. The user of such a machine has several options. One option is to simply accept the lesser quality washing action on the ends of the vehicle. Another option is to supplement the washing action of the machine with manual washing of the front and/or rear ends either with every vehicle or, as required, based on an inspection of the vehicle. A further option is to choose a pivot point location that provides the desired quality wash at either the front or the rear end of the vehicle and wash the other end of the vehicle with another piece of equipment or manually. Thus, there is a need for an improved vehicle washing machine.